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Chapter 7
Counters
•
AI Reference Trigger (ai/ReferenceTrigger)
•
AI Start Trigger (ai/StartTrigger)
•
PXI_STAR
•
Analog Comparison Event
Counter 1 Internal Output can be routed to Counter 0 HW Arm. Counter 0 Internal Output can
be routed to Counter 1 HW Arm.
Some of these options may not be available in some driver software.
Counter
n
Internal Output and Counter
n
TC Signals
The Counter
n
Internal Output signal changes in response to Counter
n
TC.
The two software-selectable output options are pulse output on TC and toggle output on TC. The
output polarity is software-selectable for both options.
With pulse or pulse train generation tasks, the counter drives the pulse(s) on the Counter
n
Internal Output signal. The Counter
n
Internal Output signal can be internally routed to be a
counter/timer input or an “external” source for AI, AO, DI, or DO timing signals.
Routing Counter
n
Internal Output to an Output Terminal
You can route Counter
n
Internal Output to any PFI <0..15> or RTSI <0..7> terminal. All PFIs
are set to high-impedance at startup.
Frequency Output Signal
The Frequency Output (FREQ OUT) signal is the output of the frequency output generator.
Routing Frequency Output to a Terminal
You can route Frequency Output to any PFI <0..15> terminal. All PFIs are set to
high-impedance at startup. The FREQ OUT signal also can be routed to DO Sample Clock and
DI Sample Clock.
Default Counter/Timer Pinouts
By default, NI-DAQmx routes the counter/timer inputs and outputs to the PFI pins, shown in
Table 7-6. To find the default NI-DAQmx counter/timer pins for the PCI-6221 (37-pin),
USB-62
xx
Screw Terminal, and USB-62
xx
BNC devices, refer to Appendix A,
